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sending meet-me conference audio to a multicast address

I want to send the audio of meet-me conference to a multicast rtp stream address. Does anybody have any idea how can this be done? There has to be a configuration for this because Cisco do this trick when bridging LMR or even POTS to meet-me conference.

The whole idea is so that the client can listen to multiple conferences at the same time. I am planning on listening to those rtp multicast stream using VLC. I was able to listen to the Paging capability and the MOH using it. Unfortunately Meet-me conference uses unicast, Wireshark revealed that to me. Can anyone please give me an idea that can point me to a direction how to do it. I know cain and abel and orkaudio can save this rtp packets to a wav file but I need a trick that will redirect those rtp to a multicast address. I have also tried udp_redirect running on slax by putting switch on monitor mode and redirect those ports to a multicast address but I can't get the program to bind or listen to all addresses even with the ifconfig -promisc.

This is what I issue to VLC to listen for Paging System using multicast ip port 2000 incase someone is interested.

vlc rtp://@

Any idea that you can throw to me would be greatly appreciated.


New Member

Re: sending meet-me conference audio to a multicast address

I guess I can answer my own post for the benefit of others. I was able to accomplish what I need by tricking the system using the paging-dn. Once I open the Meet-me conference I forwarded the call to the paging-dn.

ephone-dn 60

number 1160

description Multicast Conference Bridge

paging ip port 2000

Then I fire up trusty VLC from the command line.

C:\Program Files\VideoLAN\VLC>

vlc rtp://@

(I am planning on using batch file for this so that the user can't make any mistake.)

By issuing this command it sends an IGMP message to the switch which informs the switch that the switchport needs a copy of the multicast packets.

And that is all it takes. You just have to make sure that you have an IP phone that belongs to the paging-dn and it is in idle state. My test shows that it won't work if it is not the case but hey may be it will work on your system.

It is funny how I look at every trick that I can think of looking for an answer while the answer has been sitting in front of me all along. I love my job.


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